Search PubMed⌕ Search

Biomedical subjects

S W Li

Publications and source records attributed to S W Li.

At least 55 records · Page 3Linked to original sources
PubMed1998

Stroke and functional rehabilitation: the Chinese experience.

According to an epidemiological study of cerebrovascular disease carried out in China in 1986, the prevalence, incidence, and mortality rates were 159.93/100,000, 115.61/100,000, and 31.33/100,000, respectively. These figures were high compared to available epidemiological data for the rest of the world. This highlights the fact that, as in other countries, functional rehabilitation after stroke is an important medical and social need in China. Clinical experience shows that within a few hours to a few months after a stroke, a large proportion of patients spontaneously experience partial, or on occasion, complete recovery from neurologic symptoms. However, functional rehabilitation in medical care units is required because it assists in and accelerates the recovery of impaired function. Almitrine-raubasine has been used to improve functional rehabilitation after stroke for some time in China. By enriching the oxygen content of arterial blood, it brings more oxygen to the cerebral tissues and therefore promotes cerebral aerobic metabolism during ischemia. In the acute phase of stroke, positron emission tomography showed, in man, that almitrine-raubasine helps normalize the ischemic penumbra area, as shown by an improvement in the coupling between oxygenation and perfusion. Long after stroke, single photon emission computed tomography showed that almitrine-raubasine restores normal cerebral vasodilator response to acetazolamide. With a view to further documenting the clinical efficacy of almitrine-raubasine on the convalescent period of patients with cerebrovascular disease, a double-blind, placebo-controlled study is planned. One hundred patients with ischemic cerebrovascular disease in the territory of the carotid artery will be included 4-6 weeks after the acute onset. Two tablets daily of almitrine-raubasine or placebo will be prescribed for 3-6 months. Before treatment, there will be a 2-week washout period for all other drugs, except for antihypertensive and antidiabetic drugs. In addition to complete clinical monthly examinations, neurological functional deficit scores, Barthel index, Hasagawa Dementia scales, and CT scan are scheduled. The study results should confirm those reported in the scientific literature: although untreated patients may show spontaneous improvement, almitrine-raubasine should accelerate patients' functional rehabilitation.

Aged↗
PubMed1998

Prevalence of dementia in Chinese elderly in Hong Kong.

This study examines the prevalence of dementia in elderly Chinese aged 70 years and older in Hong Kong using a two-phase design. In phase 1, 1,034 elderly were interviewed with the Cantonese version of the Mini-Mental State Examination. Those who scored below the cutoff points and a subsample of those with scores in the normal range were interviewed in phase 2 to identify those with dementia. The overall weighted prevalence of dementia in our subjects was 6.1 +/- 0.7%, which is at the lower end of the range of rates reported in whites. Alzheimer's disease (AD) accounted for 64.6% and vascular dementia, 29.3%. Our results, together with previous studies in Chinese populations, suggest that the rates of AD in Chinese are low compared with those in whites. Substantial differences are possible in the epidemiology of dementia across cultures related to interactions of genetic and environmental factors.

Age Distribution↗
PubMed1997

Apoptosis of chondrocytes in transgenic mice lacking collagen II.

Previous work demonstrated that collagen fibrils were not detectable in the cartilage of transgenic mice homozygous for targeted inactivation of the collagen II gene. In the present work, we used the same mice to show that chondrocytes undergo apoptosis in the absence of collagen II, the major component of the extracellular matrix of cartilage. The chondrocytes in the homozygous mice had condensed nuclei, fragmentation of nuclear DNA, and decreased levels of the Bcl-2 protein. These results provide direct evidence that cartilage extracellular matrix lacking collagen II cannot support the survival of chondrocytes. In addition, the results suggest that apoptosis may play a role in degenerative connective tissue diseases such as osteoarthritis in which there is extensive tissue loss.

Animals↗
PubMed1997

Norepinephrine transmitter metabolite induces apoptosis in differentiated rat pheochromocytoma cells.

3,4-Dihydroxyphenylglycolaldehyde (DOPEGAL) is the monoamine oxidase A metabolite of norepinephrine and epinephrine. DOPEGAL, but not other metabolites, kills differentiated PC-12 cells. However, the type of DOPEGAL induced cell death, whether necrosis or apoptosis, is not known. To determine the type of cell death triggered by DOPEGAL, PC-12 cells cultured in the presence or absence of 30 microM DOPEGAL were examined by electron microscopy and DNA agarose gel electrophoresis for characteristic features of apoptosis. Results indicate that DOPEGAL induces apoptosis in these cells. Implications for degenerative diseases are discussed.

Adrenergic alpha-Agonists↗
PubMed1997

cDNA cloning and expression of bovine procollagen I N-proteinase: a new member of the superfamily of zinc-metalloproteinases with binding sites for cells and other matrix components.

Procollagen N-proteinase (EC 3.4.24.14) cleaves the amino-propeptides in the processing of type I and type II procollagens to collagens. Deficiencies of the enzyme cause dermatosparaxis in cattle and sheep, and they cause type VIIC Ehlers-Danlos syndrome in humans, heritable disorders characterized by accumulation of pNcollagen and severe skin fragility. Amino acid sequences for the N-proteinase were used to obtain cDNAs from bovine skin. Three overlapping cDNAs had an ORF coding for a protein of 1205 residues. Mammalian cells stably transfected with a complete cDNA secreted an active recombinant enzyme that specifically cleaved type I procollagen. The protein contained zinc-binding sequences of the clan MB of metallopeptidases that includes procollagen C-proteinase/BMP-1. The protein also contained four repeats that are homologous to domains found in thrombospondins and in properdin and that can participate in complex intermolecular interactions such as activation of latent forms of transforming growth factor beta or the binding to sulfatides. Therefore, the enzyme may play a role in development that is independent of its role in collagen biosynthesis. This hypothesis was supported by the observation that in some tissues the levels of mRNA for the enzyme are disproportionately high relative to the apparent rate of collagen biosynthesis.

Amino Acid Sequence↗
PubMed1997

Psychogeriatrics in South-East Asia.

A common phenomenon in South-East Asia is ageing of the population. This article describes the various stages of development of psychogeriatrics in Hong Kong, Singapore, Malaysia, Thailand, Indonesia and the Philippines. It is only in the last few years that more systematic development of psychogeriatric services has begun under the pressure of an ageing population. The model of service delivery in Hong Kong can serve as an example of development of psychogeriatric services in South-East Asia.

Aged↗
PubMed1997

Screening for dementia: a preliminary study on the validity of the Chinese version of the Blessed-Roth Dementia Scale.

Blessed-Roth Dementia Scale has been one of the most widely used rating scales in dementia. Previous studies indicated that this behavioral assessment scale is a useful tool for differentiating elderly subjects with no or minimal intellectual decline from those with cognitive deterioration. In the present study, the authors examined the validity of the Chinese version of the Blessed-Roth Dementia Scale (CDS) in Hong Kong. A total of 106 Chinese subjects were recruited from a social center, an old-age home, and psychogeriatric outpatient clinics. At a cutoff score of 3 of 4, the CDS achieved a sensitivity of 90.5% and specificity of 98.1% in differentiating demented from healthy control subjects. In the Chinese population studied, the scale was readily acceptable and considered to be an useful adjunct in screening of dementia.

Aged↗
PubMed1997

Rapid detection of bovine type II collagen-specific T-cell hybridomas.

T-cell hybridomas are powerful tools in studying the fine specificities of antigen recognition by the T-cell receptor (TCR), the structure and genetic basis of the CD3-TCR complex, and the size of the TCR alpha/beta repertoire used in response to various antigens. A technical challenge in establishing T-cell hybridomas is the early identification of antigen-specific ones. We have established a rapid and efficient ELISA method for detecting antigen-specific T-cell hybridomas. Our ELISA technique significantly reduces the time and resources required for the primary screening of antigen-specific T-cell hybrids, eliminates the need of maintaining hundreds of rapidly growing nonspecific clones, and does not require the maintenance of IL-2/IL-4 dependent cell lines such as CTLL-2 or HT-2. In addition, the ELISA technique is designed to detect both types of CD4 T-cells: Th1 and Th2, by using a mixture of anti-IL-2 and anti-IL-4 monoclonal antibodies. Therefore, we believe that our ELISA technique provides a faster, less expensive, and higher throughput screening method for the early identification of antigen-specific T-cell hybridomas than the current bioassays.

Animals↗
PubMed1997

The modified Fuld Verbal Fluency Test: a validation study in Hong Kong.

Recent studies in the West have found that verbal fluency tests are useful in the detection of dementia. In this study, the Fuld Verbal Fluency Test (FVFT) was modified and tested for its usefulness as a screening instrument for differentiating demented from normal elderly Chinese in Hong Kong. Fifty-three normal and 56 demented subjects were administered the FVFT, the Cantonese version of the Mini-Mental State Examination (CMMSE), and the Chinese version of the Hamilton Depression Rating Scale. In addition to bearing significant correlation with the CMMSE, the verbal fluency scores for all semantic categories (animals, fruits, vegetables) were found to produce significant differentiation between the normal and demented groups. However, test-retest reliability for the individual verbal fluency scores was shown to be unsatisfactory, and a composite measure was recommended for use in future screening on the grounds of its enhanced reliability.

Aged↗
PubMed1997

Vascular lesions in Chinese patients with transient ischemic attacks.

We studied 96 Chinese patients with TIAs using transcranial Doppler and duplex ultrasonography. We found intracranial stenosis or occlusion in 51% of cases and extracranial disease in 19% of cases. The most common intracranial lesion was stenosis of the terminal internal carotid artery or proximal middle cerebral artery, whereas the most common extracranial lesion was stenosis of the carotid bifurcation.

Adolescent↗
PubMed1997

SWR: an inbred strain suitable for generating transgenic mice.

Production of fertilized oocytes and generation of transgenic mice is generally more efficient using F2 hybrid embryos than embryos from inbred mice. Most F2 hybrids are of the C57BL/6 background because of its genetic and embryologic features. However, our goal of developing a transgenic mouse model for rheumatoid arthritis necessitated using a susceptible mouse strain such as DBA/1. We prepared alpha and beta T-cell receptor (TCR) chain gene constructs and microinjected them into embryos from DBA/1, SWR, (DBA/1 x SWR)F1, and (SWR x DBA/1)F1 strains. We found SWR female mice to be prolific ovulators in response to exogenous hormones, with oocyte numbers comparable to those produced by (C57BL/6 x C3H)F1 female mice. Embryos from the (SWR x DBA/1)F1 or SWR strain were large and had prominent pronuclei, whereas (DBA/1 x SWR)F1 embryos were smaller and had less visible pronuclei, similar to those of DBA/1 embryos. Therefore, the pronuclear size and visibility are features of the SWR female mice and are independent of the genotype of the fertilizing spermatozoa. Resistance to lysis after co-injection of alpha beta TCR constructs and the efficiency of generating DNA-positive founders were comparable in SWR, (SWR x DBA/1)F1, and (C57BL6 x C3H)F2 embryos. Thus, the SWR mouse is another inbred strain, in addition to the FVB inbred strain, found to be highly suitable for propagation of transgenes. Furthermore, the SWR mouse is well defined genetically, and SWR females have a high ovulation rate, comparable to that of F1 hybrid mice.

Animals↗
PubMed1996

Norepinephrine transmitter metabolite is a selective cell death messenger in differentiated rat pheochromocytoma cells.

3,4-Dihydroxyphenylglycolaldehyde (DOPEGAL) is the monoamine oxidase A (MAO-A) metabolite of norepinephrine (NE) and epinephrine (Epi). Oxidative metabolites of amines are predicted toxins. In this study we determine the toxicity of DOPEGAL, its tautomer 2',3,4-trihydroxyacetophenone (THAP) as well as NE, Epi and their oxidative and methylated metabolites in cultures of differentiated PC-12 cells. At 59.5 microM DOPEGAL, THAP and Epi, but not NE or other NE or Epi metabolites decreased PC-12 cells by 43.8%, 26.7% and 16.8% respectively. DOPEGAL toxicity was concentration and time dependent. Possible implications for degenerative diseases are discussed.

Acetophenones↗
PubMed1996

The C-proteinase that processes procollagens to fibrillar collagens is identical to the protein previously identified as bone morphogenic protein-1.

Bone morphogenic protein-1 (BMP-1) was originally identified as one of several BMPs that induced new bone formation when implanted into ectopic sites in rodents. BMP-1, however, differed from other BMPs in that it its structure was not similar to transforming growth factor beta. Instead, it had a large domain homologous to a metalloendopeptidase isolated from crayfish, an epidermal growth-factor-like domain, and three regions of internal sequence homology referred to as CUB domains. Therefore, BMP-1 was a member of the "astacin families" of zinc-requiring endopeptidases. Many astacins have been shown to play critical roles in embryonic hatching, dorsal/ventral patterning, and early developmental decisions. Here, we have obtained amino acid sequences and isolated cDNA clones for procollagen C-proteinase (EC 3.4.24.19), an enzyme that is essential for the processing of procollagens to fibrillar collagens. The results demonstrate that procollagen C-proteinase is identical to BMP-1.

Amino Acid Sequence↗
PubMed1996

Characterization of the mouse Tcra-V22 gene subfamily.

T-cell receptors (Tcrs) of higher organisms play a key role in the specific recognition of self and non-self molecules in the immune system. The large number of Tcr variable (V) genes have been organized into V gene subfamilies according to their sequence similarity at the nucleotide and amino acid level. We cloned and characterized four new members of the Tcra-V22 gene subfamily at the genomic level using a simple and sensitive technique that can rapidly clone members of any multi-member gene family. Sequence analysis reveals that the four Tcra-V22 gene subfamily members have more than 98% sequence similarity in their coding regions, at the nucleotide and amino acid levels. However, the intron between the leader and the coding region varies up to 7% between members of the Tcra-V22 gene subfamily. Comparison of the multi-member Tcra-V22 gene subfamily with other multi-member Tcra-V gene subfamilies (V2, V8, and V11), shows that Tcra-V22 is unique in that it has multiple members with nearly identical amino acid sequence and which are not inherently pseudogenes. Sequence similarity analysis of the Tcra-V22 subfamily with the prototypes of all other Tcra-V subfamilies revealed that the Tcra-V22 subfamily has the closest sequence similarity to that of Tcra-V18 (77% at the nucleotide level and 71% at the amino acid level).

Amino Acid Sequence↗
PubMed1995

Transgenic mice with targeted inactivation of the Col2 alpha 1 gene for collagen II develop a skeleton with membranous and periosteal bone but no endochondral bone.

Homologous recombination in embryonic stem cells was used to prepare transgenic mice with an inactivated Col2a1 gene for collagen II, the major protein component of the extracellular matrix of cartilage. Heterozygous mice had a minimal phenotype. Homozygous mice developed into fetuses that were delivered vaginally but died either just before or shortly after birth. The cartilage in the mice consisted of highly disorganized chondrocytes with a complete lack of extracellular fibrils discernible by electron microscopy. There was no endochondrial bone or epiphyseal growth plate in long bones. However, many skeletal structures such as the cranium and ribs were normally developed and mineralized. The results demonstrate that a well-organized cartilage matrix is required as a primary tissue for development of some components of the vertebrate skeleton, but it is not essential for others.

Animals↗